1. Technical Field
The present invention relates generally to an ion exchange membrane electrolyzer, and more particularly to an ion exchange membrane electrolyzer capable of keeping an inter-electrode spacing as predetermined.
2. Related Art
Referring to an electrolyzer used for the electrolysis of aqueous solutions, the voltages taken for electrolysis are governed by various factors. In particular, the spacing between an anode and a cathode has large influences on electrolyzer voltage. Accordingly, the inter-electrode spacing is reduced so that the electrolyzer voltage is lowered to cut down the energy consumptions necessary for electrolysis.
In an ion exchange membrane electrolyzer or the like used for the electrolysis of brine, the electrolyzer voltage is lowered by bringing three members, anode, ion exchange membrane and cathode, into close contact with one another. When it comes to a large electrolzyer with an electrode area of as large as a few square meters, however, much difficulty is experienced in bringing the anode and cathode coupled to an electrode chamber by a rigid member into close contact with an ion exchange membrane thereby diminishing and keeping an inter-electrode spacing at a given value.
With this in mind, there has been an electrolyzer proposed, wherein a flexible member is used for either one of the anode or cathode to make the inter-electrode spacing adjustable. For instance, there is an electrode put forward, in which a flexible member made of fine metal wires in the form of a woven fabric, unwoven fabric, network or the like is located on a porous electrode substrate.
Because such electrodes have a flexible member made of fine metal wires, however, when they are overly urged by counter pressure from a counter electrode, there are some problems: an uneven inter-electrode spacing due to partial deformation of the flexible member, and fine wires sticking in the ion exchange membrane.
JP-A-57-108278 or JP-A-58-37183 has also proposed an electrolyzer wherein conductive connections are made by a number of plate spring members between an electrode chamber partition side and an electrode.
The flexible electrodes using plate spring pieces are improved over those using members comprising fire wires in terms of their behavior in association with partial deformation upon pressurization. In these electrolyzers, however, all the plate spring pieces extend obliquely from a flexible cathode retainer member in the same direction.
Accordingly, as there is force acting from an electrode surface side, it causes force to act on the electrode surface, moving the plate spring member in one direction in which the plate spring member deforms by its displacement. As a result, there is a misalignment of the electrode in contact with the plate spring member. Further, when the electrode is in contact with the ion exchange membrane, there is a possibility of doing damage to the ion exchange membrane upon the misalignment of the electrode.
To address such problems, the applicant has already proposed in Japanese Patent No. 3501453 an electrolyzer wherein a plate with a plate spring member attached to it is located at a plate form of electrode chamber partition, a collector, etc., and the plate spring member is designed to have fingers or digits extending alternately in the opposite directions, so that when the electrode surface is urged against the plate spring member, the spacing between the electrode and the counter electrode is kept at a given magnitude without inconveniences such as transverse displacement of the electrode.